iTextSharp Overlay Image

Hi guys I have an instance where I have a logo image as part of some artwork..

If a user uploads a new logo I have a form field which is larger than the default logo.

I then use that form field to position the new image.

The problem is I need to set the background colour of that form field to white so that it covers the old logo in the event that the new image is smaller than the old logo..

what I have done开发者_如何学JAVA is:

foreach (var imageField in imageReplacements)
            {
                fields.SetFieldProperty(imageField.Key, "bgcolor", iTextSharp.text.Color.WHITE, null);
                fields.RegenerateField(imageField.Key);

                PdfContentByte overContent = stamper.GetOverContent(imageField.Value.PageNumber);
                float[] logoArea = fields.GetFieldPositions(imageField.Key);
                if (logoArea != null)
                {
                    iTextSharp.text.Rectangle logoRect = new iTextSharp.text.Rectangle(logoArea[1], logoArea[2], logoArea[3], logoArea[4]);

                    var logo = iTextSharp.text.Image.GetInstance(imageField.Value.Location);
                    if (logo.Width >= logoRect.Width || logo.Height >= logoRect.Height)
                    {
                        logo.ScaleToFit(logoRect.Width, logoRect.Height);
                    }
                    logo.Alignment = iTextSharp.text.Image.ALIGN_LEFT;
                    logo.SetAbsolutePosition(logoRect.Left, logoArea[2] + (logoRect.Height - logo.ScaledHeight) / 2);
                    // left:  logoArea[3] - logo.ScaledWidth + (logoRect.Width - logo.ScaledWidth) / 2

                    overContent.AddImage(logo);
                }
            }

The problem with this is that the background colour of the field is set to white and the image then doesn't appear.. i remove the SetFieldProperty and RegenerateField commands and the image replacement works fine..

is there a way to set a stacking order on layers?

Annotations (such as form fields) are always on top of page contents. Annotation Z order is just the order of the annotations array on a given page.

Page content Z order is just the order everything appears in the content stream. New drawing operators go on top of proceeding operators.

If you want to cover your old image, draw a white box over it and then draw the new logo over top that. No need to worry about annotations.

Actually, all you really need to do is not set the background color of the imageField. You're already scaling the new logo to match the size of the old one.

However, if you really must draw that white box, it's fairly simple:

overContent.setColorFill(iTextSharp.text.Color.WHITE);
overContent.rectangle( logoRect );
overcontent.fill();